Many modern greenhouses utilize elongated metal hollow tubing to construct various elements of the structure. Both square and rectangular cross-sectional shapes are utilized, as well as round and elliptical shapes. These are usually standard in cross sectional size, and typically measured by the outside dimensions of the cross-section.
Several wall thicknesses of steel are available in standard gauge dimensions (such as 12 gauge, 14 gauge, 16 gauge, etc.) to allow for a wide range of structural strength combinations. When hollow structural tubes are created from rigid materials that can be extruded, (such as aluminum or plastic), or from cold rolled, steel sheeting; the range of wall thicknesses is limitless.
Most of these structures are assembled on site, in an erector-set-like fashion. In many cases, erection is performed by employees of the owner of the building, who are non-experts the practice of building structures. They also usually have limitations on the tools available to them; although, standard wrenches, drills, saws, etc. needed to build an erector set are usually available and familiar. Because the height of walls and rough opening sizes for equipment needing to be installed usually vary from structure to structure, tubing members are usually shipped in long standard lengths. Measurements are then taken on site as the structure is built, and the standard tubes are cut down to the desired lengths.
A typical gable end of a greenhouse will usually be formed by a series of vertical hollow tubes being mated to horizontal hollow tubes to create openings for necessary fans, shutters and doorways. Most of these junctures of tubing members create 90.degree. angled to interconnections, and usually employing 90.degree. angle brackets. The typical angle bracket is usually first bolted, or otherwise fastened, to the side of a vertical post and then the horizontal member is fastened to the other side of the 90.degree. angle bracket. If two angle brackets are used at a joint, this basically creates a two point mechanical junction at the joint (even if more than one fastener is used in each side of each 90.degree. angle bracket).
The roof line of many greenhouses presents a Quonset-hut type or a bowed roof outline. When the vertical hollow tubing meets the outline of the roof bows, the junctions that are created form angles less than, or greater than, 90.degree.. These angles change consistently along the roof bowing. The use of 90.degree. angle brackets to form connections that are not 90.degree., are just not practical. In those cases, specially adapted end brackets are needed to join the vertical or horizontal members to the changing angles of the roof bow. These special brackets also rely on fasteners to clamp the special bracket to one or both sides of the bow, and then fasteners to connect the bracket to the vertical or horizontal structural member. This resulting connection of the prior art also usually results in a two point mechanical junction at the joint.
It is a principal object of the invention to provide a tubing member that can utilize an end portion of it's own length of material to readily construct an interconnection with another tubing member of the same cross-sectional size, using standard and readily available fasteners, but without the use of 90.degree. angled or special brackets, and without the need for welding these members to each other.
It is another object of the invention to provide biasing grooves continuously along the longitudinal dimensions of the tubing, to selectively allow the end sides of the tubing to be split away and then flared outward, in a controlled manner, so as to create the fastening flanges that allow the two tubes to be reliably conjoined together at various angles of inclination.
A further object of the invention is to allow the internal dimension of two opposing longitudinal sides of the tube to be equal to, or slightly exceed, the external dimensions of the other two opposing longitudinal sides which will enable the two unflared ends of the tube to is span and overlap(?) the narrower dimension of the same sized tube.
A yet further object of the invention is to allow the person who is erecting the new structure to utilize one sized (squared or rectangular cross-sections) structural members to create both horizontal posts and vertical beams without needing various sized structural members, or various sized brackets, for accomplishing variously angled connections.
A still further object of the invention is to allow the installer to create end joints and tubing interconnections mechanically with simple fasteners that result in a three or four point mechanical interconnection on many junctures.
Another object of the invention is to create stable multi-rigid tubing interconnections that allow the external surfaces of the completed structure to be relatively free of protruding lugs and edge brackets, which protrusions would hinder fastening of sheet-like materials over the framed structure.
Still another object of the invention is to allow the tube to selectively allow the sides of the tubing to be split away and then flared outward, in a controlled manner, so to create the fastening flanges that allow the tube to be reliably conjoined with flat surfaces or the edges or corners of flat surfaces.
Still another object of the invention is to allow the tube to selectively allow the sides to of the tubing to be reliably conjoined with structural members that are rounded, elliptical, angular, larger, or smaller than the tube.